This proposal aims to reveal the genes important for regulating alcohol consumption and the development of addiction. Drug addiction is the process by which the brain learns to depend on a drug, and crave for it in its absence. Alcohol dependence is tightly linked to changes in gene expression and gene pathways in the brain. An effective therapy therefore must rely on the ability to target many alcohol-related genes. MicroRNAs (miRNAs) are a class of small, non-coding RNAs that have been found to regulate gene expression and the translation of these genes into protein, providing them the potential to affect many gene networks simultaneously. The extensive synaptic plasticity associated with alcohol dependence relies on many mRNAs, which is in turn controlled by specific microRNAs. Gene therapy with microRNAs provides a potential treatment for alcohol dependence. Over the past decade a number of microRNAs have been proposed to regulate learning through interactions with local translation of mRNA into protein, specifically in the synapse (pre-synaptic terminals and post-synaptic densities - the sites of communication between nerve cells in the brain). However, little is known about the microRNAs involved in the regulation of mRNA translation during alcohol dependence. We have developed a protocol and can now analyze synaptic RNAs, and to compare synaptic expression levels to the total homogenate expression (non-synaptic compartments) of the same animal. The results show detection of many mRNAs and microRNA families known to be enriched in the synapse. The use of mice undergoing an alcohol drinking paradigm will enable us to identify alcohol-responsive synaptic RNAs. Here we propose to investigate alcohol-responsive microRNAs and mRNAs in the synapse using a microarray technique to study expression levels for thousands of RNAs simultaneously. The microRNAs which are most affected by alcohol and which target many synapse-specific, alcohol- responsive mRNAs will be chosen for genetic manipulation. These microRNAs will then be over-expressed and under- expressed, and we will study the resulting effect on alcohol consumption. Targeting synapse-specific mRNAs with a microRNA as a potential treatment for alcoholism is novel. This study is the first to modulate a microRNA in an alcohol self-administration paradigm, and is the first study to measure many gene networks with microarrays in response to the genetic modulation. Findings will impact basic and translational science of drug dependence and prevention, spurring the development of new treatments. In addition, ancillary benefits may be achieved for many psychiatric disorders that are a consequence of pathological takeover of normal learning mechanisms, such as depression, retardation and schizophrenia, effectively pushing the boundaries of our understanding of these 'diseases with no cure'.